Vibratory Reverse Osmosis Treatment of Hampton Downs Leachate BY CHRIS LOBB OCTOBER 2015

Transcription

1 Vibratory Reverse Osmosis Treatment of Hampton Downs Leachate BY CHRIS LOBB OCTOBER 2015

2 Contents 1. Background on the Hampton Downs Landfill 2. Landfill Leachate key issues 3. The Problem increasing costs 4. Treatment Options Considered 5. Reverse Osmosis Trial - VSEP 6. VSEP Technology 7. HD LF Leachate Treatment Plant 8. Black Mudfish / Consents 9. Sustainability 10. Lessons Learnt

3 Hampton Downs PARRC Power and Resource Recovery Centre

4 Hampton Downs Landfill Opened in 2005 at cost >$30m 35 year consent 360 Ha site, 87 Ha landfill footprint 7 stages 70m max depth 42 Mm3 of airspace capacity 38M tonnes of refuse capacity Currently disposing 500,000tpa Expected life greater than 35yrs

5 Pre-development landform

6 Filling Stage 1

7 Filling Stage 2

8 Filling Stages 3,4,5,6 and 7

9 Landfill Leachate Key Issues Cost All leachate tankered off site Treatment and disposal at Mangere WWTP 150 to 300m 3 /day Cost $22.00/m 3 Total Cost per annum >> $ 1m / year

10 Landfill Leachate Key Issues Quantity Leachate volumes generated are highly dependent upon rain infiltration Year Leachate mm of rain Total Landfill Tankered Area Offsite (m3) (mm) (m2) , , , , , , , , , ,000

11 Landfill Leachate Key Issues Quality Current disposal cost dependent on quality as well as quantity cbod5 -range 400 to 4000 ppm Sulphides 1.0ppm, treated onsite to ensure <5ppm Ammonia range 300 to 1600ppm Boron range 0.4 to 40 ppm

12 Leachate Constituent NZDWS ANZECC Irrigation + ANZECC water quality 90% Raw leachate g/m 3 unless stated Arsenic Cadmium Chromium NA Copper Nickel Lead Zinc * Manganese Fluoride NA Barium NA NA Total sulphide * NA Total Alkalinity as CaCO3 5,800 NA NA NA Total Sodium 1,431 NA NA NA Chloride 1,466 NA NA NA Total Ammoniacal -N 930 NA NA 1.43 Nitrate - N NA 3.4 Sulphate 96 NA NA NA cbod5 g O2/m3 1,898 NA NA NA COD g O2/m3 4,346 NA NA NA Total Boron Total Iron NA Note 1: * zinc and sulphide values are guidelines not Maximum Acceptable Values. Note 2: + Irrigation values for short term use (20 years).

13 The Problem Increasing Costs and Risk Total costs increasing with landfill size by $1.0m every 5 years $2.5m Transport Treatment Disposal Opex by 2020 Increasing future capital - more storage tanks, tankers Risk - WWTP changing waste acceptance criteria, price No local disposal options without significant treatment

14 Treatment Options Processes considered Evaporation Chemical Physical Biological Reverse Osmosis Objective disposal to local WWTP or onsite (air, land,water)

15 Treatment Processes Not Favoured Evaporation Use of landfill gas (LFG) to evaporate leachate Uneconomical for ESL Lost electrical revenue is $38.00/m 3 of leachate Compared to current cost $22.00/m 3 Capital cost similar to Reverse Osmosis Evaporation to air Limited by Auckland average humidity 70 85%

16 Reverse Osmosis Best Option Reverse Osmosis Attractive blanket removal of contaminants Established RO history -used at landfills Equador - 0.5mg/l Boron, 0.5mg/l Ammonia Lab work on HD leachate Good rejection rates, colloidal solids fouling New Logic Research Vibratory RO

17 Reverse Osmosis Trial New Logic Research - San Francisco Vibratory separation enhanced processing (VSEP) used at several landfills Mitigates colloidal fouling of membrane Trial plant flown to Auckland VSEP unit and Spiral unit

18

19 VSEP Separation Technology

20 VSEP Trial Results Pressure study to determine flux Cleaning study 60 73% recovery of permeate Boron reduction 26 to 6mg/l Ammonia reduction 730 to 15mg/l Conductivity 1300 to 6mS/m All other contaminants compliant

21 VSEP Separation Technology Oscillating movement of membranes Helps eliminate membrane blinding Allows free access of the liquid to the membrane pores Shear created causes suspended solids to be held above the membrane surface which are washed away with laminar flow.

22 VSEP Separation Technology Membrane filter stack mounted on a resonating mechanical drive system A 20 hpdrive motor spins an eccentric lobe Drives a large steel mass at the bottom Once speed increases whole system resonates at a harmonic frequency 19mm peak to peak displacement

23 VSEP Separation Technology Membrane filter stack mounted on a resonating mechanical drive system A 20 hpdrive motor spins an eccentric lobe Drives a large steel mass at the bottom Once speed increases whole system resonates at a harmonic frequency 19mm peak to peak displacement

24

25 HDLF Leachate Treatment Plant New Treatment Plant New Logic Research and Syngineering Design Capacity 300m3/ day 6 VSEP units + 4 Spiral units Capex $6.0 million Opex~ $6.50/m 3 excldepreciation Justified by Opex Savings ~ $0.5m/yr 65 75% recovery as permeate Concentrate returned to landfill

26 HDLF Leachate Treatment Plant Under construction Completion Q2 2016

27

28 Black Mudfish Ecological study Relic species black mudfish found HDLF wetlands and Clune stream Iwi treasured species (toanga) DOC Species at Risk -Relictual Hibernate in summer (estivate) High quality water environment

29 Consents Land Irrigation Consents issued Only when soil moisture deficiency 15Om 3 /hectare per 3 day period, 1 Oct to 31 March 20 year term, expiring 2034 Stream Disposal Consent issued ANZECC 90% Protection of Species Conductivity 20mS/m Annual average Boron 0.4mg/l, Iron 0.2mg/l, Sodium 1.0mg/l, Ammoniacal Nitrogen 0.5mg/l 15 year term, expiring 2029

30 Innovation, Environment & Sustainability New Leachate Treatment Plant For 40,000m 3 /yrdisposed to land/stream Save 1600 tanker trips per year 179,000 km/yr 85,000 litres of diesel per year 227 tonnes CO2e / year Recycled water for site use

31 Lessons Learnt to date! Project capex was $4m grew to $6m Balance of plant underestimated Design and cost estimate omissions Detail engineering design required at earlier stage for capex accuracy

32 Questions?

33 Meet the new us: EnviroNZ